I'm using 2.6-dev compiled on 2015-08-16.
I got a crash loading a game, I attach the crashdump.txt file.
I'm on Deian testing with AwesomeWM, resolution 1280x800 video card Nvidia GeForce Go 7300 with proprietary drivers.
Here you are some output that was present in the terminal (clearly the interesting part is at the end):

Music: track changed from van_geoscape to dbsea.
UI_ExecuteCallAction: Node from path "root.messages.dock@createChild" not found (relative to "geoscape.add_geoscape_object").
UI_ExecuteSetAction: node "root.messages.messagesystem.message.ufo1.type@string" doesn't exist (source: geoscape.add_geoscape_object)
UI_ExecuteSetAction: node "root.messages.messagesystem.message.ufo1.id@string" doesn't exist (source: geoscape.add_geoscape_object)
UI_ExecuteSetAction: node "root.messages.messagesystem.message.ufo1.siteModel@src" doesn't exist (source: geoscape.add_geoscape_object)
UI_ExecuteSetAction: node "root.messages.messagesystem.message.ufo1.message@string" doesn't exist (source: geoscape.add_geoscape_object)
GAME_SetMode_f: Mode 'campaign_main' not found
Calling subsystems
...subsystem 'campaign' - saved
...subsystem 'research' - saved
...subsystem 'base' - saved
...subsystem 'hospital' - saved
...subsystem 'market' - saved
...subsystem 'employee' - saved
...subsystem 'aircraft' - saved
...subsystem 'alien base' - saved
...subsystem 'interest' - saved
...subsystem 'installation' - saved
...subsystem 'mission' - saved
...subsystem 'ufostores' - saved
...subsystem 'production' - saved
...subsystem 'messagesystem' - saved
...subsystem 'stats' - saved
...subsystem 'nations' - saved
...subsystem 'transfer' - saved
...subsystem 'xvirate' - saved
...subsystem 'messageoptions' - saved
...subsystem 'triggerevents' - saved
XML Written to buffer (500796 Bytes)
Music: track changed from dbsea to Crystan-Geosphere04.
UI_ExecuteCallAction: Node from path "root.messages.dock@createChild" not found (relative to "geoscape.add_geoscape_object").
UI_ExecuteSetAction: node "root.messages.messagesystem.message.ufo3.type@string" doesn't exist (source: geoscape.add_geoscape_object)
UI_ExecuteSetAction: node "root.messages.messagesystem.message.ufo3.id@string" doesn't exist (source: geoscape.add_geoscape_object)
UI_ExecuteSetAction: node "root.messages.messagesystem.message.ufo3.siteModel@src" doesn't exist (source: geoscape.add_geoscape_object)
UI_ExecuteSetAction: node "root.messages.messagesystem.message.ufo3.message@string" doesn't exist (source: geoscape.add_geoscape_object)
GAME_SetMode_f: Mode 'campaign_main' not found
Calling subsystems
...subsystem 'campaign' - saved
...subsystem 'research' - saved
...subsystem 'base' - saved
...subsystem 'hospital' - saved
...subsystem 'market' - saved
...subsystem 'employee' - saved
...subsystem 'aircraft' - saved
...subsystem 'alien base' - saved
...subsystem 'interest' - saved
...subsystem 'installation' - saved
...subsystem 'mission' - saved
...subsystem 'ufostores' - saved
...subsystem 'production' - saved
...subsystem 'messagesystem' - saved
...subsystem 'stats' - saved
...subsystem 'nations' - saved
...subsystem 'transfer' - saved
...subsystem 'xvirate' - saved
...subsystem 'messageoptions' - saved
...subsystem 'triggerevents' - saved
XML Written to buffer (502864 Bytes)
Music: track changed from Crystan-Geosphere04 to karlmacklin_geoscape.
UI_ExecuteCallAction: Node from path "root.messages.dock@createChild" not found (relative to "geoscape.add_geoscape_object").
UI_ExecuteSetAction: node "root.messages.messagesystem.message.ufo0.type@string" doesn't exist (source: geoscape.add_geoscape_object)
UI_ExecuteSetAction: node "root.messages.messagesystem.message.ufo0.id@string" doesn't exist (source: geoscape.add_geoscape_object)
UI_ExecuteSetAction: node "root.messages.messagesystem.message.ufo0.siteModel@src" doesn't exist (source: geoscape.add_geoscape_object)
UI_ExecuteSetAction: node "root.messages.messagesystem.message.ufo0.message@string" doesn't exist (source: geoscape.add_geoscape_object)
Music: track changed from karlmacklin_geoscape to karlmacklin_geoscape.
Music: track changed from karlmacklin_geoscape to van_geoscape.
GAME_SetMode_f: Mode 'campaign_main' not found
Cvar 'sel_load_slot;' wasn't found
Loading savegame xml (size 43359)
Loading savegame
...version: 4
...game version: 2.6-dev
...xml Size: 502864, compressed? y
Shutdown gametype 'Campaign mode'
Error: Mem_CheckSentinels: bad memory footer sentinel [buffer overflow]
pool: Client: Local (per game)
alloc: src/client/cgame/cl_game.cpp:#450
free: src/client/cgame/cl_game.cpp:#445